Desert Power Company and Energy Concepts Company jointly announced the startup of a combined chilling and power system at a vegetable processing facility in Blythe, California.
The system generates 830 kW of electricity from two natural gas fired reciprocating engines, and 160 tons of 25°F chilling from the engine waste heat. An additional 120kW peak is supplied from solar photovoltaic panels.
Located on the western bank of the Colorado River, Blythe is an amazingly productive crop growing area. Fisher Ranch Corporation processes the produce grown on over 12,000 acres of the Palos Verde Valley, including melons, corn, broccoli, and lettuce. A cold storage warehouse covering more than half an acre is chilled to 34°F in order to chill this produce prior to shipment all across the United States.
With a typical summer daytime temperature of 115°F, this requires 500 tons of chilling, in order to deliver 6,000 gpm of 32°F water to air handler cooling fans throughout the cold store. The combined electric load for chillers, air handlers, and processing ranges from 600 to 1,000 kW. Summer electricity has become scarce and very costly in this part of California. Hence Fisher Ranch decided to implement lower cost electric supply options.
The natural gas fired engines operate at about 35% efficiency, and have both SCR for NOX removal and also VOC catalyst. The waste heat powered ThermoChiller is supplied both jacket heat (at 220°F) and exhaust heat from both engines.
The aqueous ammonia working fluid is directly heated by the exhaust in a heat recovery heat exchanger. The 160 tons of refrigeration is supplied directly to a cold room some 250 feet distant, where 1,900 gpm of chill water cascades over the ammonia evaporator coils.
The ThermoChiller is located next to a cooling tower, which supplies it 600 gpm of 80°F cooling water. The footprint of the ThermoChiller is 8 feet by 8 feet.
When adding the electricity displaced by the 160 tons of chilling (~160 kW), the effective efficiency of converting natural gas to electricity increases from 35% up to 42%. Also, the additional refrigeration capacity increases plant reliability, and allows the refrigeration compressors to operate in a more efficient regime. These factors combine to provide substantial savings in cost of electricity to Fisher Ranch.
Most gas-fired reciprocating engine installations with extensive emissions reduction have an installed cost of more that $2,000 per kW, not including waste heat powered chilling.
The Fisher Ranch installation was below $1,500 per kW, including the chilling. The cost was further reduced by the California Self-Generation Incentive Program.